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dma-mapping: Add a new dma_need_sync API

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Add a new API to check if calls to dma_sync_single_for_{device,cpu} are
required for a given DMA streaming mapping.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200629130359.2690853-2-hch@lst.de
This commit is contained in:
Christoph Hellwig 2020-06-29 15:03:56 +02:00 committed by Daniel Borkmann
parent 2bdeb3ed54
commit 3aa9162500
5 changed files with 30 additions and 0 deletions
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8
Documentation/core-api/dma-api.rst
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@ -204,6 +204,14 @@ Returns the maximum size of a mapping for the device. The size parameter
of the mapping functions like dma_map_single(), dma_map_page() and
others should not be larger than the returned value.
::
bool
dma_need_sync(struct device *dev, dma_addr_t dma_addr);
Returns %true if dma_sync_single_for_{device,cpu} calls are required to
transfer memory ownership. Returns %false if those calls can be skipped.
::
unsigned long

1
include/linux/dma-direct.h
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@ -87,4 +87,5 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs);
int dma_direct_supported(struct device *dev, u64 mask);
bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr);
#endif /* _LINUX_DMA_DIRECT_H */

5
include/linux/dma-mapping.h
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@ -461,6 +461,7 @@ int dma_set_mask(struct device *dev, u64 mask);
int dma_set_coherent_mask(struct device *dev, u64 mask);
u64 dma_get_required_mask(struct device *dev);
size_t dma_max_mapping_size(struct device *dev);
bool dma_need_sync(struct device *dev, dma_addr_t dma_addr);
unsigned long dma_get_merge_boundary(struct device *dev);
#else /* CONFIG_HAS_DMA */
static inline dma_addr_t dma_map_page_attrs(struct device *dev,
@ -571,6 +572,10 @@ static inline size_t dma_max_mapping_size(struct device *dev)
{
return 0;
}
static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
{
return false;
}
static inline unsigned long dma_get_merge_boundary(struct device *dev)
{
return 0;

6
kernel/dma/direct.c
View File

@ -530,3 +530,9 @@ size_t dma_direct_max_mapping_size(struct device *dev)
return swiotlb_max_mapping_size(dev);
return SIZE_MAX;
}
bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr)
{
return !dev_is_dma_coherent(dev) ||
is_swiotlb_buffer(dma_to_phys(dev, dma_addr));
}

10
kernel/dma/mapping.c
View File

@ -397,6 +397,16 @@ size_t dma_max_mapping_size(struct device *dev)
}
EXPORT_SYMBOL_GPL(dma_max_mapping_size);
bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
{
const struct dma_map_ops *ops = get_dma_ops(dev);
if (dma_is_direct(ops))
return dma_direct_need_sync(dev, dma_addr);
return ops->sync_single_for_cpu || ops->sync_single_for_device;
}
EXPORT_SYMBOL_GPL(dma_need_sync);
unsigned long dma_get_merge_boundary(struct device *dev)
{
const struct dma_map_ops *ops = get_dma_ops(dev);